The present invention relates to a suction attachment for a vacuum cleaner in general, and more particularly to a suction attachment having a housing component which may be used by itself or in combination with a brush component accommodated in the interior thereof.
There are already known various attachments of the type mentioned above, in most of which the brush component is accommodated in the interior of the housing component and is biased toward a retracted position thereof in which the bristles of the brush component are received within the housing component, while the brush component is capable of assuming an extended position relative to the housing component in which the bristles of the brush component extend beyond the housing component and into contact with a surface to be cleaned during the use of the attachment. The displacement of the brush component between the positions thereof is, in most instances, achieved by means of an actuating element which extends from the interior of the housing component to the exterior thereof to be accessible to the user of the attachment, and which is to be depressed both when the brush component is to be displaced towards its extended position, and to its retracted position, the actuating element always returning to its initial position after displacing the brush component relative to the housing component. The attachment has a central exhaust port or conduit communicating with the interior of the housing component and also with the vacuum cleaner during the use of the attachment, so that the vacuum cleaner exhausts air and any contaminants entrained therein from the interior of the housing component through the exhaust port.
In one attachment of this type, a single actuating element is provided which is capable of displacing the brush component relative to the housing component either from the retracted toward the extended position, or from the extended toward the retracted position. In this proposed attachment, there is employed a so-called slotted link switch having a cam plate provided with a guide slot and the actuating element has a projection which is guided in the guide slot of the cam plate. The guide slot of the cam plate is so configurated that it arrests the actuating element in a lower position thereof in which the actuating element holds the brush component in the extended position thereof. In other words, the actuating element does not return to its initial position upon displacing the brush component into the extended position. Now, when the actuating element is depressed again, the projection of the actuating element is guided in the guide slot and along an inclined surface, pushes the slotted link switch aside about a turning axis of the latter and thus lets the brush component return into its retracted position.
This proposed attachment is disadvantageous in that an additional structural element, that is the so-called slotted link switch, is needed for arresting the brush component in the individual positions thereof, as well as for the mechanical cooperation of the various components. It is furthermore of a significant disadvantage, that due to the mechanical construction as well as to the mechanical cooperation of the various elements, the so-called slotted link switch must conduct a tilting movement about its turning axis. This results in an economically unsupportable expenditure both in terms of cost and complexity of construction; furthermore, the various elements of this proposed attachment must be manufactured and assembled with extreme care inasmuch as otherwise any misalignment or tolerance imprecisions will result in rapid destruction either of the axle of the switch or of the bearing in which such axle is received.
In addition thereto, such a construction requires for its operation the provision of a plurality of springs the properties of which must be constantly supervised during the manufacture thereof.
Moreover, there has also been already proposed a different attachment for use in connection with vacuum cleaners which is also capable of being operated by means of only one actuating element for displacing the brush component relative to the housing component between the extended and retracted position of the brush component. In this particular attachment, a ratchet mechanism is provided in the actuating element, which brings the brush component in its extended position by means of a turnable bracket. The ratchet mechanism includes, at the two ends thereof, projections which enclose an angle of 180.degree. with one another, which are turned during each actuation of the actuating element by 90.degree. and thus, on the one hand, press the brush component via the bracket downwardly and, on the other hand, release the brush component for displacement toward the retracted position thereof. The ratchet mechanism serves to prevent unintended retraction of the projections during the exertion of a downwardly directed force on the attachment.
Experience with this particular type of attachment has shown that the actuation of the brush component by means of the bracket which is of a generally U-shaped configuration, is particularly disadvantageous. Inasmuch as the bracket acts on the brush component substantially in the central region thereof, it is always possible to turn one side of the brush component about the point where the brush component is mounted on the bracket, and into the interior of the housing component, so that the brush component is incapable of assuming a stable position relative to a smooth surface to be vacuum cleaned.
It is further disadvantageous in this construction of the attachment that the distribution of the various forces acting on the components of the attachment is so disadvantageous that the projections are subjected to excessive forces.